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Only VX900C is supported by Release 5.0; all other VX products are supported by VX 4.9 and previous.

IPv6 is available only with the VX900C 5.0 and later (running on WIN 7). The VX900C supports IPv6, in conjunction with IPv4.

What is an IPv6 address?

  • IPv6 addresses are 128-bit identifiers (16 bytes) used for addressing the IPv6 interfaces on the nodes. An example of an IPv6 address is as follows: 2367:EF01:2345:6789:ABCD:EF01:2345:6789.
  • An IPv6 address ranges from 0000:0000:0000:0000:0000:0000:0000:000 to fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff.

How is an IPv6 address configured?

An IPv6 Address can be configured on the VX900C in one of the following ways:

  1. Auto-configured Address
  2. Static Address

For detailed information about IPv6 configuration, see IPv6 Configuration.

IPv6 Address formats accepted in VX900C

  • Preferred Format of IPv6 address - Examples:



  • Alternate Format (Shortened) of IPv6 address - Examples:

Omit leading zeros. Omit leading zeros in string. For example, IPV6 1050:0000:0000:0000:0005:0600:300C:326b can be written as 1050:0:0:0:5:600:300c:326b.

Double colon. Double colons ( :: ) can be used in place of a series of zeros. For example ff06:0:0:0:0:0:c3 can be written as ff06::c3.

IPv6 Address Prefix Definitions in VX900C

  • The high-order bits of an IPv6 address specifies the network; the rest of the bits specify the particular addresses in that network. As a result, all the addresses in one network have the same first N bits. Those first N bits are called the "prefix".  The VX uses "/N" to denote a prefix.
  • In the VX, IPV6 addresses are written with their proper prefix included in Ethernet adapter, IP Route etc.
  • Examples:
    • 2001:db8::6:1/64, The "/64" indicates that this is an address with a 64 bit prefix
    • 2001::/16, The “/16” indicates that this is an address with a 16 bit prefix
  • IPv6 Address type and their respective notations



Address type

Binary prefix

IPv6 notation


00...0  (128 bits)



00...1  (128 bits)





Link-Local Unicast



Global Unicast

everything else

everything else



  • IPv4 and IPv6 Address Equivalents


IPv4 Address

IPv6 Address

Broadcast Addresses


Unspecified Address is

Unspecified Address is ::

Loopback Address is

Loopback address is ::1

Public IP Addresses

Global Unicast Addresses

Subnet mask or Prefix length

Prefix Length notation only

  • Compatibility Addresses (IPv4 compatible, IPv4 mapped, 6to4 addresses) are not supported in VX.
  • Access to CLI/VXbuilder/VXwatch with Link Local addresses in the VX900C is limited.

Dual Stack Capability

The VX900C can be configured to assign both IPv4 and IPv6 interfaces on an adapter at the same time. The IPv6 address can be either a Static address (manually configured) or an Auto-configured interface.

When the VX sends a packet to an IPv6 address, it initially looks at the Neighbor cache to get the MAC address for the IPv6 Address for which traffic should be sent. If the Neighbor cache entry exists and the VX knows the MAC Address, it sends traffic/packet to that particular MAC in the network. For more information about the show neighbors command, see Command Line Interface S Commands.

  • When a VX node is upgraded to 5.0 from a previous version, the existing adapters will have the DAD Transmit count set to 0.
  • After a system reboot, for each interface IP, the DAD message is transmitted twice the number of times configured for that adapter.

IPv6 License

In order for IPv6 to be configured in the VX, the IPv6 license must be installed (through VXbuilder or CLI). See Installing a License Key for obtaining a license key.

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